[Waverley ARS] Drivers for a 8x8 grid addressable array of LEDs

[Adam Carmichael]

Hi all,

I've started designing a circuit for a cluster of 64 tri-colour LEDs
which I'm going to use to make the next (first) piece of decorative
furniture for my bedroom.

The project is divided into two boards, the first of which is the
"display board" - it will house the 64 LEDs in an 8x8 square. The second
board is a control board containing a PIC18F4550 microcontroller,
connected via 4 8pin headers.

(See the attached image for a schematic)

1 header contains all the cathodes for each row of LEDs, the other 3
headers contain the red, green and blues for each column. By example,
this means: cathode pin 1 is row 1 and (due to a silly mistake in my
schematic which I will fix soon) red pin 8 is "column 1 red". This
allows me to turn on any one LED at any instant using just 32 pins total.

I can then use a mind hack called "persistence of vision" to turn on
multiple LEDs "simultaneously". By quickly flashing them on and off, I
can make it appear like multiple LEDs are on.

My question to the group is this:

What would be the best way to go about driving these, and where would
you put the resistors?

Right now I am thinking about a resistor for each cathode, and that's
where I put, say, 8 BC337 transistors. Does anyone know of an IC package
that might be a suitable replacement for the transistors?

Thanks in advance,

73 VK2JSI... Adam

-- 
Adam "carneeki" Carmichael - VK2JSI, ex VK2FNRD
p: +61 415 37 1990
w: http://bigneek.com (personal); http://carneeki.net (business)
e: carneeki at carneeki.net
i: 2207644